CHICKPEA PLANT IT’S MOLECULAR REGULATION OF ROOT HAIRS: A REVIEW

In dicotyledons, Fe3+ must be reduced to Fe2+ before uptake and transport of this essential macronutrient can occur. Ambler et al demonstrated that reduction along the root could be observed by the formation of a stain, Prussian blue (PB), Fe4 [Fe(CN)6]3 n H2O (where n = 14-16). This stain, which is an insoluble precipitate, forms at the reduction site when the nutrient solution contains Fe3+ and ferricyanide. In 1972, Chaney et al proposed a model which suggested that the Fe3+ reduction site occurred outside the cell membrane; however, no physical evidence to support the model was presented at that time. A more recent study using the PB stain indicates that rapid reduction of Fe3+ occurs in a region of the root containing young root hairs. Furthermore the most pronounced activity occurs in plants that are deficient in Fe. To more precisely localize the site of Fe3+ reduction, scanning electron microscopy (SEM), x-ray analysis, and transmission electron microscopy (TEM) were utilized to examine the distribution of the PB precipitate that was induced to form in roots.

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Techniques for preparing the Lolium perenne coleorhiza for scanning electron microscope evaluation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100124239 ◽

1992 ◽

Vol 50 (1) ◽

pp. 766-767

Author(s):

Susan B.G. Debaene ◽

John S. Gardner ◽

Phil S. Allen

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Lolium Perenne ◽

Morphological Study ◽

Root Hairs ◽

Inner Pressure ◽

Water Potentials ◽

Radicle Emergence ◽

Standard Fixation ◽

Scanning Electron

The coleorhiza is a nonvascular sheath that encloses the embryonic radicle in Poaceae, and is generally the first tissue to emerge during germination. Delicate hairlike extensions develop from some coleorhiza cells prior to radicle emergence. Similar to root hairs, coleorhiza hairs are extremely sensitive to desiccation and are damaged by exposure to negative water potentials. The coleorhiza of Lolium perenne is somewhat spherical when first visible, after which a knob forms at a right angle to the caryopsis due to inner pressure from the elongating radicle. This knob increases in length until the radicle finally punctures the coleorhiza. Standard fixation procedures cause severe desiccation of coleorhiza cells and hairs, making morphological study of the coleorhiza difficult. This study was conducted to determine a more successful process for coleorhiza preservation.

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SEM and fluorescence imaging of callose deposition in root hair tips and suspension cultures of Streptanthus tortuosus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161047 ◽

1990 ◽

Vol 48 (3) ◽

pp. 698-699

Author(s):

K.S. Walters ◽

R.D. Sjolund ◽

K.C. Moore

Keyword(s):

Cell Wall ◽

Root Hair ◽

Cultured Cells ◽

Root Hairs ◽

Callus Cultures ◽

Callose Deposition ◽

Culture Cells ◽

Wall Structures ◽

Ultraviolet Illumination ◽

Callose Formation

Callose, B-1,3-glucan, a component of cell walls, is associated with phloem sieve plates, plasmodesmata, and other cell wall structures that are formed in response to wounding or infection. Callose reacts with aniline blue to form a fluorescent complex that can be recognized in the light microscope with ultraviolet illumination. We have identified callose in cell wall protuberances that are formed spontaneously in suspension-cultured cells of S. tortuosus and in the tips of root hairs formed in sterile callus cultures of S. tortuosus. Callose deposits in root hairs are restricted to root hair tips which appear to be damaged or deformed, while normal root hair tips lack callose deposits. The callose deposits found in suspension culture cells are restricted to regions where unusual outgrowths or protuberances are formed on the cell surfaces, specifically regions that are the sites of new cell wall formation.Callose formation has been shown to be regulated by intracellular calcium levels.

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